System of fluid fuel supply for multiple burner operation



p 1959 E. nuossou 2,902,086

SYSTEM OF FL UID FUEL SUPPLY FOR MULTIPLE BURNER OPERATION Filed April12. 1955 \NVENTOR M ATToRNEYS United States Patent' -O SYSTEM OF FLUIDEUEL'SUPRLYFOR MULTIPLE BURNER :QPERAIION E ric Dott Hobson,ShandomScotl-and, assig'nor-to Yarrow and Company Limited,-Scotstown,GlasgW,'Sc0tland Application April 12, -1955,-S erial N0..-50'0,-895

Claims priority, application Great Britain April 22, 1954 .2 Claims.(Cl. 158-363) This invention relates to-oil burning installations .forfurnacesof thekind wherein oil issupplie'd totthe burner by suitablepumping means and the operational range of .the burner .is controlled byproviding means for bypassing surplus quantities of oil at apointupstream of .the burner discharge' orifice. Accordingly,inoperating such installations, .when the burner isto ,operateat-maximum output the by-pass will be closed so that the-whole of theoil will be injected-into the :furnace, but when it .is'desired tooperate at a lower rating, the byepass willbe opened to permitacontrolledtquantity oftoilqto be bypassed. The burners of this-kind:are generally k-nownas spill type burners.

In order that the .oil reaching the burner has the requisite viscositytoensure eflicientatomisatiomit is known to provide a heating device inthe 'oil flow line and to pro- \vide high and lower pressure pumps-forfeeding the oil to the burner. Hitherto a-majordifficulty of operating,oil burning installations ,of this kind has beenarranging for thesatisfactory disposalzof the hobby-passed oil, and it is an object ofthepresentinvention tto provide-means whereby this oil is safely disposedof ;in a manner that will improve the overall efficiencyofithetinstallation.

According to the present invention ;an oil burning .installation for afurnace having spilltype burners comprises apump connectedin the oilfiow aline fordelivering .oil.to oil heating:means,,a.second pumpoperating at ,a higher pressure than the first for 'delivering;oil.discharged from the heater to'the oilburners of [the furnace andmeans for collecting the spilled ,oilzby-passed from .the blJIllflS'fiSsurplus to requirements .anddelivering it into the oil flow line at apointintermediatethe heater and-the first mentioned pump.

By this arrangement thehot spilled oil is recirculated to the oil systemand its heat is accordingly conserved thereby enabling the heatingdevice to operate withrless input heat than would otherwise bethe case.

The heating device maybe in the form of a heat exchanger includingconcentric flowpassages through which steam and oil tobe heated arecaused to flow. A temperature control device is provided at theinfeed-of the heat exchanger to control the supply-of heating steaminaccordance with the oil-temperature it is desired tomaintain attheoutfeed of the heateror at theentry -to-the burner so as to ensure thatwhen itreaches the atomisingnoz-zle of the burner it will be at asuitable -'temperature-and viscosity for .efiicient atomisation.

To enable .the invention to be fully understood it will now be describedwith reference to the accompanying drawing, which illustrates indiagrammatic forman oil burning installation accordingtotone aembodimentof the invention.

As shown in the accompanying drawing, an oil-burning Patented Sept. 1,1959 ICC installation includes a low pressure pump 1 having its inletconnected to a pipe ,2 connected :to a storage tank (not shown)containing oil which Will normally beat a relatively low temperature. Asshown a strainer 3-is provided in the pipe 2. The discharge side of thepump 1 is connected with apipe 4 leading to amixing chamber 5 whosedischargetside is connected to a pipe .leadingto the infeeds of a pair,ofheat exchangers 6. Each heat exchanger includes-oil passages 7, .7 aand steam passages 8, 8a, the steam passages having inlets 9 .and anoutlet 10. Asshown in the drawing, the mixingchamber is an enlargedright cylinder with its axis mounted in a-vertical plane. The cold oilinlet pipe 4 connects to the center of the bottom of chamber 5.

The oil discharged from the heat exchangers flows through a pipe 12 andfilter 12a to a pump 13 which is adapted to operate at a higher pressurethan the pump 11 and deliver the heated oil through the pipe 14 to theburners 15 of thefurnace. Aby-pass conduit 16 is provided for eachburner and is connected .with a main bypass pipe 17 leadingto themixingcharnber 5. T he operationalrangepf .the burners is controlled byadjusting a regulator valve 18 intheby-pass pipe 17 so as to vary theamount of oil by-passed from the burners.

.Spilled oil surplus torequirements of the burners passes through theconduits .16 and by-pass 17, to the mixing chamber 5 Where it-isrecirculatedthroughthe oil system by mixing with the relatively cold oilbeing pumped by the pump 1. The temperature ofthisoil is thus raised bythe hotspilled oil and the mixed oil then flows to spilled fromtheburners intorder totensurethat'the spilled oil will readily flowintothe chamber irrespective ;of the quantity spilled. .It is .notedthatlow pressure pump 1 supplies soil to an enlarged cylindricalmixing-chamber -5 and that a high pressure; pump-13 supplies-oil .underhigh pressure touthe burners 15. The pressure till the bypass .17 ismaintained by.oil--fr0m the ihighpressure' pump :13

fed through the spillway in the burners. Preferably the arrangement issuch that the {pressure in the mixing chamber is at a-minimumwhenthearate 'of' spill registers its maximum, that is, at ,periods whenthe :burners are operating at low demand.

It is desirable to maintaina substantially constant pressure, adequateto prevent vaporisation of the ;oil, at the inlet side of the highpressure pump 13 and to ensure this a -by-pass pipe ,20 is connectedbetween the discharge and inlet-sides of'the low pressure pump 1, apressure responsive valve 21 being provided which is .arranged to openautomatically if the .pressure at the-suction side-of the high pressurepump 13 exceeds a predetermined figure, for example 10 lbs.above'atmospherie pressure. As shown the-valve ;21 has adiaphragm'disposed in a diaphragm chamber 22, one side'ofthe diaphragmbeing connected by a-pipe 23, to the suction side .of the pump 13and-the otherbeing connected to atmosphere bya pipe 23a so that whenthepressure at the suction side of the pump 13 exceeds thepredeteiminedfigure, *for example 10 lbs. above atmospheric pressure,:the diaphragm will be actuated to open the valve 21.

-It will be'noted' that the pipe 23 is connected :in the flow line topump 13 downstream of the filter 12a and accordingly the pressure at thesuction side of the pump 13 can be accurately controlled and will not beaffected by the condition, for example choking up, of the filter.

To prevent damage to the 'high pressure pump in the event that for somereason the burner valves are not open when the installation isoperating, a by-pass 24, including a pressure relief valve 25, isprovided between the discharge and inlet sides of the high pressure pump13. This valve is, however, only a safety device and under normalconditions it will remain closed. A by-pass 31 having a relief valve 32is also provided connecting the inlet and outlet sides of the lowpressure pump 1.

The pumps 1 and 13 are designed to run at constant speeds and as shownare driven through suitable gearing by a common prime mover 26 such as asteam turbine through shafts 36 and 38. If desired, however, each pumpmay be independently driven.

When the burners are required to operate at light load, instead of allthe burners remaining in operation, any desired number can be completelyshut down by the valves 14a, 17a and for example only two burners leftin use. In this case the supply of oil would be curtailed by running thepumps 1, 13 at reduced speed, no adjustment of the heaters beingrequired. When both pumps are driven by a common prime mover, thecontrol of the latter would automatically effect a simultaneous andequal reduction in the speed of both pumps.

The temperature of the heat exchangers 6 is adapted to be adjusted toensure that the oil will be at a temperature such as to ensure eflicientatomisation when it reaches the burners.

According to one form of temperature control, the steam inlets 9 of theheat exchangers 6 are connected to a common steam supply line 9a whichhas a valve A which is connected with a heat responsive element or de-'vice B located in the flow line 14. The arrangement is such that thesupply of heating steam to the exchangers 6 is automatically controlledin accordance with the temperature of the oil discharged from the heatexchangers.

If desired either of the heat exchangers 6 may be shut down by closingthe respective oil inlet and discharge valves 6a, 6b and the appropriatesteam inlet valve 912. It will be noted that the arrangement of thetemperature control is such that the valve A will operate to control theflow of heating steam irrespective as to whether one or both heatexchangers are in use.

By this means when the burner is operating under light load and arelatively large quantity of hot spill oil is being by-passed and mixedwith the incoming cold oil, the supply of heating steam to the heatexchangers can be greatly reduced without impairing the efficiency ofthe installation.

An important advantage of the invention is that the hot spill oil issafely disposed of and the danger of fire or explosion which mightresult if the hot oil were returned to the fuel tank, is entirelyeliminated.

A further advantage is that, by adjustment of the setting of the oiltemperature control according to the grade of oil being consumed, theviscosity and pressure of the oil supplied to the high pressure pump 13will remain unaltered regardless of its viscosity as it is being drawnfrom the storage tank. In consequence the pressure characterised at theoutput of this pump will be unafiected by the grade and temperature ofthe oil entering the low pressure pump 1, whether it be the normallyused heavy boiler oil or any lighter and less viscous oil.

An important advantage of positioning the heater be tween the low andhigh pressure pumps is that the heater may be designed to operate at thelow pressure of the oil being supplied by the low pressure pump. Anadvantage of positioning the filter 12a between the pumps 1, 13 is thatthe pressure in the filter cannot exceed that of the pump 1, as therelief valve 32 will automatically open if the back pressure due to thefilter becomes eXQt SS By maintaining constant viscosity and pressure ofthe fuel at the inlet of the high pressure pump 13 and selectingsuitable pressure-output characteristics at the outlet side of thispump, correct burner inlet pressure is assured for any desired burneroutput by adjustment of the single regulator valve 18 which controls therate at which spilled oil flows through the by-pass 17. The provision ofadditional valves to control the flow of oil to the burners isaccordingly obviated.

The regulator valve 18 may be operated by remote control from aninstrument panel.

It will be understood that any desired number of burners may be includedin the installation, each burner being connected to the oil fiow lineleading from the high pressure pump and connected with a by-pass conduit16 at a point upstream of their discharge orifices.

The pumps 1 and 13 may be of any convenient type and the heat exchangermay take other forms than that shown.

The installation may be made adaptable for various grades of fuel oiland to this end one or more valve controlled connections, such as 28 maybe provided for the flow line on the suction side of the pump 1. Forexample a diesel oil supply pipe may be connected to the connection 28and the supply to the pipe 2 shut off by closing the valve 29 and thediesel supply opened by opening the valve 30.

The invention is particularly adapted for oil burning furnaceinstallations for marine propulsion plant.

I claim:

1. In an oil burning installation for a furnace including a plurality ofspill type burners, an oil fiow line connected with the supply side ofthe burners, a heater in said flow line, a mixing chamber connected insaid flow line upstream of said heater, a low pressure pump fordelivering oil fuel through said chamber to the heater, a by-passconduit connecting the downstream side of each of said burners with saidmixing chamber, a high pressure pump connected in the flow line betweenthe heater and the supply side of the burners for delivering the heatedoil to the burners, said mixing chamber comprising a cylindrical member,an axially disposed inlet port in the bottom thereof communicating withsaid low pressure pump for supplying oil at a relatively lowtemperature, annularly disposed nozzle means mounted in the lowerportion of said cylindrical member and connected to said bypass conduitand directed to inject oil in streams tangentially of the flow path ofthe oil delivered from said low pressure pump, the pressure in saidmixing chamber being maintained less than that of the oil being spilledfrom said burners by the combination of high and low pressure pumps, andmeans for regulating the operation of said burners comprising a singlevalve in said by-pass conduit for regulating the amount of oil by-passedfrom said burners into the said mixing chamber.

2. An oil burning installation for a furnace having a series of spilltype burners, comprising an oil flow line connected with the supply sideof the burners, a heater in said flow line, a low pressure pump fordelivering oil to the heater, a mixing chamber connected in said flowline between said heater and said low pressure pump, a common by-passconduit for receiving hot oil spilled over from all said burners anddelivering it into said mixing chamber, a high pressure pump connectedin the flow line between the heater and the supply side of the burnersfor supplying oil heated by said heater to said burners, means forautomatically controlling the heater to ensure that the oil dischargedtherefrom will be at a predetermined constant temperature, said mixingchamber including a cylindrical member, an inlet portion axiallydisposed in the bottom of the cylindrical member and connected to saidlow pressure pump, nozzle means positioned within the lower end of saidcylindrical member and connected to said bypass for delivering hot oilspilled from said burners to the lower end of said cylindrical 6 memberwhereby said hot oil is directed through said References Cited in thefile of this patent nozzle means, the pressure in said mixing chamberbeing maintained less than that of the oil being spilled from UNITEDSTATES PATENTS said burners by the combination of high and low pres-1,554,869 McAndreWs Sept. 22, 1925 sure pumps, and means for controllingthe operation of 5 2,219,917 Crosiar Oct. 29, 1940 said burnerscomprising a single valve in said by-pass 2,263,913 Bargeboer Nov.25,1941 conduit operable to regulate the amount of hot spilled 2,355,693Aldrich Aug. 15, 1944 oil permitted to flow into said by-pass conduit.2,368,164 Schumann et 3 9

